The Role of Anthocyanins in Wine
Anthocyanins contribute little to the taste of wine. However, because anthocyanins readily polymerize with tannins, they play an important role in tannin retention in and aging. There is a close association between anthocyanins and wine color. Research into this phenomenon has yielded a complicated set of interactions that gives insight into color stability of wine.
Anthocyanins are classified by the position of hydroxyl and methyl groups on the second phenyl ring. Based on this, anthocyanins are separated into five groups; cyanins, petunins, peonins, malvins and delphinins.
The presence and concentration of each of the five groups of anthocyanins is varietal specific and changes with changing environmental conditions and viticultural practices. The proportion of five classes has a huge impact on the color and color stability in a wine.
Color and color stability are largely affected by the number of hydroxyl and methyl groups. The number of free hydroxyl groups is directly related to blueness; the number of methyl groups is directly related to redness. An example of this phenomenon is malvin. It is the primary anthocyanin in red grapes, and not surprisingly, it has the greatest degree of methylation and thus the reddest color.
Anthocyanins in Nature
Anthocyanins developed in the leaves of photosynthetic plants as protection from the photo-damage of UV and blue-green light. These pigment molecules are effectively sunscreen for plants. In addition to their primary function, they also act as anti-oxidants, protecting plants from free radical oxidation. Anthocyanin synthesis is activated by direct exposure to UV radiation and is tightly associated with veraison.
This is important because anthocyanins are found in high concentrations in the skins of black grapes and contribute to the color of red wine. If you kept the skins of red grapes separate from the pulp, you could make white wine red grapes. This is used in the production of Sparking Wine.Related Articles
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